@Bitstreams, if you have enabled Activity 24/7 wrist HR tracking and toggle the general setting for Power Saving On and Off, you may be hitting a settings bug where the wrist HR lighting is on at the same time power saving is on. This will definitely consume some extra battery over a week.
For me, the scenario is:
24/7 wrist HR tracking ON
Power Saving ON
start a training exercise using HR belt with wrist HR disabled
On completion of training and return to clock mode, view backside of watch to see wrist HR lights flickering
If I go to Settings/General after 4) and turn off Power Saving, wrist HR will then be recorded, turning Power Saving back on will stop the flickering. If I don’t change the Power Saving setting, the wrist HR lights will continue flickering, but the HR value is not recorded in the HR widget time series nor will it be shared to SA daily summary.
Agree with @inkognito that the screen backlight is a more likely culprit for a faster discharge, but an increase to 5 to 10% battery consumption per day may just be the wrist HR unexpectedly running.
